Mid-Infrared Quantum Scanning Microscopy via Visible Light Beyond Spatial Correlations

The mid-infrared (MIR) spectral region, spanning from 2- to 25- (Formula presented.), provides access to rich chemical information through the vibrational modes of functional groups, lipids, and other complex molecules. However, conventional imaging in this range remains limited by challenges in generating MIR light and by the lack of mature detection technologies. Quantum imaging with undetected light (QIUL) offers an alternative approach by using photon-pair sources in which the sample is illuminated with MIR light while detection and image reconstruction are carried out at visible wavelengths. We report the first QIUL technique that achieves diffraction-limited resolution without relying on spatial correlations of the photon-pair, thereby overcoming a fundamental limitation of all previous implementations. This work establishes induced coherence without induced emission as the essential physical resource underlying QIUL and redefines its operational boundary, extending its applicability to regimes where spatial correlations are weak or absent. Our results represent a conceptual advance in quantum imaging and open the way toward practical and cost-effective MIR microscopy based on visible detection.